Anvil subprocess hangs writing stdout

[jaeaster]

Version

└── ethers v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf)
    ├── ethers-addressbook v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf)
    │   ├── ethers-core v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf)
    ├── ethers-contract v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf)
    │   ├── ethers-contract-abigen v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf)
    │   │   ├── ethers-core v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf) (*)
    │   ├── ethers-contract-derive v0.17.0 (proc-macro) (https://github.com/gakonst/ethers-rs#b2fc9fdf)
    │   │   ├── ethers-contract-abigen v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf) (*)
    │   │   ├── ethers-core v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf) (*)
    │   ├── ethers-core v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf) (*)
    │   ├── ethers-providers v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf)
    │   │   ├── ethers-core v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf) (*)
    ├── ethers-core v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf) (*)
    ├── ethers-etherscan v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf)
    │   ├── ethers-core v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf) (*)
    ├── ethers-middleware v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf)
    │   ├── ethers-contract v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf) (*)
    │   ├── ethers-core v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf) (*)
    │   ├── ethers-etherscan v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf) (*)
    │   ├── ethers-providers v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf) (*)
    │   ├── ethers-signers v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf)
    │   │   ├── ethers-core v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf) (*)
    ├── ethers-providers v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf) (*)
    ├── ethers-signers v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf) (*)
    └── ethers-solc v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf)
        ├── ethers-core v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf) (*)
├── ethers v0.17.0 (https://github.com/gakonst/ethers-rs#b2fc9fdf) (*)

Platform
21.6.0 Darwin Kernel Version 21.6.0: arm64

Description
I have tests that spawn an anvil process and make a lot of rpc calls.

When using warn-level logging, which suppresses the stdout of rpc calls, my tests run fine.
When using info logging, my tests hang awaiting a response from anvil that never arrives.

Dropping the stdout handle for the anvil subprocess fixes my issue.

See related issue for more details: foundry-rs/foundry#3414

[mattsse]

thanks for checking.

proposing dropping the stdout handle when we return Anvil instance as the fix, we don't need it anyway.

do you want to take this on?